Very strange problem! I know you already checked the md5sum of the iso image, but double-check again to be sure.
Sometimes, I've heard people having problems booting from DVD-RW discs, but succeed with DVD-R disks; but thought USB would have booted right if that were the sole problem.
Long Shot Here -- but might as well give it a shot!
xot wrote:I could not find anything in the BIOS setting that looked like I could set the SATA DVD drive from AHCI/RAID to IDE/Compatibility mode.
Assuming it's a PC you've got and not a laptop, the other thing that you might want to try is plugging the sata cable from DVD into a different sata port on the motherboard.*
Try moving it to one farthest away from where it is now. If there are two separate groupings (eg. 4 on one area, 2 on another area) of sata connectors on the motherboard, try moving it from the group it's connected to now to the other.*
If you're not familiar with inside of computer, there will be two cables connected to the DVD player. One cord will connect to the power supply; the other will go from the DVD player to the motherboard (the main board with all the circuitry and lots of things connected to it). UNPLUG
computer before opening case; touch metal
on inside of case first
(to discharge any static electricity); if possible keep one hand on metal of case inside while unplugging the connector to the motherboard and plugging back into a different sata port. (You'll know which are sata ports because they will look the same as one you just unplugged from.)